Resinous compositions from coal acids and polyfunctional amines and method for making composite products thereof



y 1959 w. ARCHER ET AL RESINOUS COMPOSITIONS FROM com. ACIDS ANDPOLYFUNCTIONAL AMINES AND METHOD FOR MAKING COMPOSITE PRODUCTS THEREOFFiled Dec. 20, 1 56 6 cqm oouna.

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Wes/e L. flrcer koeri S. blonif'gomery John L. Lang United States PatentRESINOUS COMPOSITIONS FROM COAL ACIDS AND POLYFUNCTIONAL AMINES ANDMETH- OD FOR MAKING COMPOSITE PRODUCTS THEREOF Wesley L. Archer, RobertS. Montgomery, and John L. Lang, Midland, Mich., assignors to The DowChemical Company, Midland, Mich., a corporation of Delaware ApplicationDecember 20, 1956, Serial No. 629,669

Claims. (Cl. 26037) This invention relates to thermosetting,resin-providing compositions that are comprised of certaincross-linkable reaction products or adducts of polyfunctional aminecompounds with coal acids and which are capable of being cross-linkedand thermally cured to resinous products having a pronounced utility forbeing employed in an adhesive capacity or as a binder material, or both,for any of a wide variety of inert filler substances. The inventionbears especial reference to such resin-providing compositions that areexceptionally Well-suited as a binder (or as a precursor thereof) forthe preparation of formed composite structures with inert, siliceousfiller substances such as glass fibers and sand, in particular. Theinvention is also concerned with the integral formed compositestructures that may be prepared and obtained by thermosetting and curingthe resin-providing compositions after they have been dispersed over andthroughout a desired inert filler substance.

It is among the principal objects of the invention to furnishthermosetting, resin-providing compositions that are comprised of thereaction products of polyfunctional amine compounds and polycarboxylicacids from the oxidation of coal and like carbonaceous materials.

It is also among the objects of the invention to furnish variousthermoset resin products from such compositions as well as integral,composite structures that utilize them.

One particular object of the invention is to furnish a thermosettingresin-providing composition that is especially and advantageouslyadapted to function as a binder (or as a precursor thereof) for glassfibers and the like to obtain various desirable composite structurestherewith including mats, panels and similar constructions.

Another particular object of the invention is to furnish a thermosettingresin-providing composition that is especially and advantageouslyadapted to function as a binder (or as a precursor thereof) for sand toprepare various desirable refractory structures therewith includingshell molds, hot top devices and similar constructions.

A further object of the invention is to provide methods for thepreparation of integral composite structures from inert fillersubstances, particularly siliceous fillers such as glass fibers andsand, that utilize the resin-providing compositions of the invention.

Additional objects, purposes and advantages of the invention will bemanifest in the following description and specification.

According to the invention, a thermosetting, resinproviding compositionis comprised of a crosslinkable reaction product or adduct of apolyfunctional amine compound and a mixture of the polycarboxylic acidsthat may be obtained from the oxidation of coal and the likecarbonaceous materials which, for convenience, are hereinafter referredto as coal acids. The cross-linkable coal acids adduct mayadvantageously be obtained as the reaction pro-duct of about equivalentamounts of the polyfunctional amine compound and the polycarboxylic coalacids starting material (taking the polyfunctionality of each of thereactant ingredients into account). This provides a coal acids adductwhich has an optimum maximum potential for cross-linking andinterreaction upon being subsequently thermoset and exposed to heat atelevated curing temperatures. However, if it is desired, suitableadducts for many purposes can also be obtained as the products ofreactions between non-equivalent quantities or" the polyfunctionalreactants. Nonetheless, it is generally desirable for the proportions ofeither polyi'unctional reactant that may be utilized in excess ofstrictly equivalent stoichiometric requirements to be main tained atless than about a 2:1 equivalent parts ratio.

The cross-linkable coal acids adduct may be readily and advantageouslyprepared in a suitable solvent medium, such as in water, low molecularweight alcohols such as methanol and ethanol and the like. In manyinstances, it may even be prepared in surplus quantities of thepolyfunctional amine compound when it is available as liquid havingsuitable fugacity to allow for its ready removal from the reaction masswhen it is desired to terminate the adduct-forming reaction. Thereaction between polyfunctional reactants may generally be accomplishedat normal room temperatures. It is usually sufficiently exothermic innature so as to frequently require that the reaction mass be cooledduring the reaction in order to obtain optimum coal acids adducts. Aftertheir preparation, the coal acids adducts may be isolated from solutionin the reaction mass and recovered, if so desired, as solids which haveappearances that may vary from crystalline structures to somewhat glassyappearing products. In many instances, however, they may be utilized forsubsequent application directly in the solution of the reaction mass inwhich they were obtained. The coal acids adducts, after their initialpreparation, may be cross-linked and further self-reacted by subjectingthem to heat at an elevated thermosetting and curing temperature inorder to provide thermoset, cross-linked, cured resinous products thathave the indicated characteristics and utilities.

Composite structures may be prepared by mixing or compounding one of thesolid, cross-linkable coal acids adducts with a desired inert fillersubstance and subsequently thermo-setting the adduct after it is inintimate association with the filler. In many cases, however,particularly for binding glass fibers and for preparing refractorycompositions with sand and equivalent inert fillers, it may be ofgreater advantage and a more decided benefit to prepare the compositestructures by first applying or interblending the cross-linkable coalacids adduct while it is in solution (which, as has been indicated, maybe the solution in which it was prepared) to or with the inert fillersubstance and subsequently drying and heat curing the applied adduct toa cross-linked, thermoset resin structure that at least partiallyenvelops and binds together or coalesces the inert filler.

While requirements may vary when preparing composite structures withindividual inert filler substances and in other applications, it isusually desirable for many applications to employ a sufficient quantityof the crosslinkable adduct to ensure, upon curing of the formulatedcomposition to a composite structure, that between about 2 and 15percent by weight of the thermoset resin, based on the weight of theformulated composition, is present in the composite structure. However,for some purposes (according to conventional practices), much more ofthe resin may be required. Thus, when such fillers as wood flour areutilized or when certain fiber reinforced plastic structures are beingfabricated, a major proportion of the composite structure, as in theneighborhood of 50 to 70 or more percent by weight, may advantageouslyconsist of the resin binder.

The cross-linkable coal acids adducts of the invention may be thermosetand cured at applied temperatures or in curing atmospheres havingtemperatures between about 300 F. and 1200 F. for periods of timebetween about several seconds and several hours depending, as will beappreciated by those skilled in the art, upon the particularconfiguration and composition that is involved. Usually (and frequentlynecessarily) the thermosetting or curing times that are required areinversely proportional to the temperature that is utilized. The coalacid adducts of the invention, as a general rule, can be satisfactorilythermoset and cured to suitable resin structures by beating them to anactual resin temperature between about 300 and 600 F. for a period oftime between about 10 seconds or less and an hour or more, depending onthe particular heating techniques that are involved and theheat-exchanging efiiciencies that are realized. Besides the moreconventional means for heating, the resins may also be cured suitablyunder the influence of dielectric heating.

Although the resin-producing coal acid adducts of the present inventionare adapted to be utilized in and of themselves in the preparation ofmoldings and other shaped articles, they are, as has been indicated,especially desirable for employment in or as thermosetting adhesives,binders, molding powders, fillers and the like in which capacity theymay be utilized independently or in combination with other ingredients.Thus, they may be employed suitably as the adhesive ingredient in theproduction of ply-wood and similar laminate articles of construction.Particular benefit, as mention, may be derived when the adducts areemployed as binders for the preparation of composite structures fromvarious inert filler substances including silicious fillers,carbonaceous fillers (such as graphite, coke breeze, powdered coal andthe like) and relatively analogous fillers including mineral andsynthetic fibers, asbestos, fiy ash, various blast furnace andpowerhouse slags, mica flour, wood flour and the like fibrous orgranular substances that are substantially inert to the resin-providingcompositions and do not melt, fuse excessively or decompose at thethermosetting and curing temperatures which may be involved in thefabrication of the desired composite structures. Exceptional advantagesare involved when such inert silicious filler substances as glass fibersand sand are bound together with the thermoset and cured coal acidsadducts of the invention. One of the halves of a shell mold preparedfrom a sand composition coated with a thermosetting coal acids adduct inaccordance with the invention is illustrated in Figure 1 of theaccompanying drawing. A mat of glass fibers bound together with a curedresin from a coal acid adduct of the invention is depicted in Figure 2of the drawing.

The coal acid adducts are particularly useful to form a resinous binderfor glass fibers which is exceptionally resistant to failure due to suchspontaneous combustion phenomenon which is frequently referred to aspunking. In the utilization of the adducts to prepare punk-resistantbinders for glass fibers, it is generally preferred to apply the adductfrom a relatively dilute solution, advantageously an aqueous solution,that contains between about 5 and 20 percent by weight, and moreadvantageously from about 6 to 12 percent by Weight, based on the totalweight of solution of the dissolved coal acids adduct. As is apparent,enough of the solution should be applied to the mass of glass fibers tobe bound to ensure that the desired quantity of the thermoset resinwhich is formed will be available for binding the fibers, taking intoaccount such factors as solution drainoff and the like. A cured resinbinder content between about and 15 percent by weight is oftentimessatisfactory for most glass fiber mats. It is usually beneficial topermit excess quantities of the adduct-containing solution to drain offbefore subjecting the intermediate mass to a suitable thermosetting andcuring temperature. Mechanical means, such as aspirating or forced draftapparatus, may oftentimes be employed with advantage to accelerate thedrainage of excess quantities of the coal acids adduct solution. Theheat that is applied at the curing temperature may ordinarily be usedwith benefit to simultaneously dry the applied solution of the coalacids adduct dispersed on the mass of glass fibers prior to or duringits cross-linking and thermosetting at the elevated thermal condition.The curing of the applied solution to form the binding resin for theglass fibers may generally be accomplished suitably at temperaturesbetween about 300 and 600 F. for periods of time between about an hourand two minutes or so. Curing at 450- 550 F. for 5 to 2 minutes isoftentimes highly satisfactory. The fibrous glass composite structuressuch as mats, batting, panels and the like that are bound together withthe thermoset and cross-linked adducts of the invention are strong,relatively rigid, moisture-resistant and exceptionally resistant topunking. In the last-mentioned category in particular, they are superiorto the phenolic resin binders that have been utilized conventionally forsuch purposes.

The coal acids adducts are also extremely useful for the preparation ofresin-bounded shell molds from sand and for like refractory structures.The shell molds which may be prepared with the resin-providingcompositions of the invention may be fabricated in a manner similar tothat which is utilized in the so-called Croning process which has beendescribed in F.I.A.T. Final Report No. 1168 (dated May 30, 1947) by theField Information Agency, Technical, United States Department ofCommerce. Shell molds, as is well known, are finding increasing favorfor employment in and to facilitate metal casting operations since theyameliorate many foundry techniques. They do not require the use of asmuch sand as is employed for conventional green sand moldmakingoperations and eliminate much of the hazard and unpleasantness due todust and powder that obtains in the practice of the old technique. Inaddition, they generally permit better castings to be obtained and arelighter and less cumbersome to handle and manipulate than areconventional sand molds. The adducts may also be utilized, as has beenmentioned, in sand compositions for the fabrication of hot top deviceswhich are utilized in the pouring of hot top ingot molds of iron andsteel and for similar refractory structures.

The sand compositions for refractory structures may be formulated bythoroughly intermixing the sand with the coal acids adduct after it hasbeen dried to a cross-linkable powder. Or, with usually greateradvantage, they may be prepared by intimately intermixing a relativelystrong solution, such as an aqueous solution that contains at leastabout 50 and preferably in the neighborhood of 70 percent or more byweight, based on the weight of the solution of the dissolvedcross-linkable adduct, with the sand by continuous or batch mulling orintensive mixing procedures. The coal acids adduct/sand compositions mayeither be fabricated as a wet mix into desired shapes prior to beingthermoset or may be dried in a dry atmosphere at a non-thermosettingtemperature of between about room temperature and 225 F. in order toform a particulate, coated sand composition that may be formed as a dry,free-flowing granular composition into desired structures prior to beingcompletely thermoset.

While in the process of drying a wet sand mixture in this manner, it mayoften be beneficial to subject it to continued agitation in order tofacilitate its being obtained in a suitable granular condition. It mayalso be beneficial to screen the dried, thermosetting coated sandformulation to obtain a desired particle size. In order to prepare shellmolds in accordance with typical dump box techniques, it is usuallypreferred to dry the sand composition when it has been prepared bymixture with a solution of the cross-linkable coal acids adduct and toprepare the free-flowing coated sand by any desired granulationprocedure so that its average particle size characteristics are suchthat the preponderance of the formulation, usually at least about 70percent by weight, is not larger than about 40 mesh in the US. StandardSieve Series.

In the preparation of sand compositions for refractory structures, it isdesirable to employ a suificient quantity of the coal acids adduct thatis utilized to provide between about 2 and and preferably between about3 and 8 percent by weight of the cross-linked resin binder in thecomposition, based on the total weight of the composition. It isgenerally advantageous to utilize only as little a quantity of the resinbinder in the composition for refractory structures as may be necessaryin order to obtain suitably strong structures. In this way therefractory structures can be readily obtained with adequate porosity andminimized tendency to smoke and fire excessively during burn out or tocause carbonization when contacted by the molten metal that thestructure is intended to receive.

The coal acids adduct/sand compositions, when they are prepared as dry,free-flowing, coated sand mixtures, may generally be pre-formed into adesired structure, such as a shell mold, by placing them in contactwhile in a suitably thick layer with or against a heated pattern for aperiod of time from about to 60 seconds with pattern temperaturesbetween about 500 and 800 F. Wet mixtures may generally be pre-formedinto desired structures such as hot top devices or shell molds bycompacting or compressing them against a suitable pattern or in asuitable mold form under pressures, for example, in the neighborhood of80l20 pounds per square inch as may be developed with a hydraulic orpneumatic ram or the like. Core blowing techniques may also be employedto distribute a wet mixture against pattern surfaces or in mold forms.Regardless of whether dry or wet mixtures are used, the pre-formedstructures may be suitably thermoset and cured by exposing them totemperatures between about 350 and 750 F. for periods of time betweenabout 10 seconds and several minutes, depending again upon theparticular configuration and composition that is involved in thestructure being cured.

The cured refractory structures that may be obtained, including shellmolds and hot top devices, are, as has been indicated, generally strongand rigid products. They have high gas permeabilities due to theirexcellent characteristics of porosity. They have good surface smoothnessand dimensional stability which permit fine detail molds and the likefor metal casting purposes to be obtained. In addition, the refractorystructures that may be obtained by practice of the invention have littletendency to adhere to the surface of the hot metal after it has beencooled and solidified and may be readily stripped or removed therefrom,usually disintegrating easily and cleanly upon sharp impact or withother means for their physical removal.

The coal acids adduct/sand formulations that can be prepared with theresin-providing compositions of the invention have the significantadvantage of being free from readily flammable substances andconsequently safer to use, especially in the fabrication of shell molds,than are many of the phenolic resin coated sand compositions that haveheretofore been used for such purposes.

Any ordinary sand (or other refractory material) that, advantageously,has a fineness in accordance with the values proposed by the AmericanFoundrymans Society (AFS) which is in the numerical range between aboutand 180 may be utilized for the preparation of refractory structuresbound together with the thermoset, cross-link coal acids adducts of theinvention. Such sands, for example, as the types known as Berkeley FloatSand, Juniata Sand, Lake Sand, Vassar Sand, Wedron Sand, Gratiot BankSand, Portage 4060 Sand and the like may be beneficially employed. It isdesirable that the sand be clean and substantially free from foreignmetal oxides, clay, moisture and organic matter. In many cases, it maybe more advantageous to employ tively coarse sands that have an AFSfineness number between about 25 and 75 are ordinarily more desirablefor utilization in formulations with the coal acids adducts of theinvention that are intended for fabrication into hot top devices and thelike.

The coal acids that are employed to prepare the resinproviding adductsof the invention may be identical with or similar to those which may beobtained by the oxidation with gaseous oxygen, which may be contained inthe air, of an aqueous alkaline slurry of a finely divided carbonaceousmaterial selected from the group consisting of coal and coke that hasbeen obtained by the carbonization of coal at temperatures beneath about1300 F. Coal acids that have been prepared by the nitric acid oxidationof suitable carbonaceous materials are also generally satisfactory. Suchcoals that are of the varieties known as anthracite, bituminous,sub-bituminous and lignite and other low grade coals are generallysuitable for production of coal acids. Satisfactory cokes are thoseproduced according to conventional techniques from coal at a temperaturebeneath about 1300 F. The utilization of higher coking temperaturesfrequently causes the cokes that are obtained to be graphitic andrendered unsuitable for conversion to coal acids in satisfactory yields.

The free coal acids product is a hygroscopic, usually yellowish,essentially Water-soluble material that is believed to be substantiallycomprised of various aromatic polycarboxylic acids. The averagemolecular weight of the coal acids that are ordinarily obtained isfrequently in the neighborhood of 250. Their average equivalent weightis generally about and seldom less than 75 or more than 90. Theyordinarily appear to have an average of 2.5 to 5 carboxylic groups permolecule with an apparent average of 3 to 4 being common. While theirexact chemical nature and constitution may be somewhat conjectural, theyevidently contain considerable quantities of triand tetra-carboxylicbenzene acids as well as aromatic acids having more complex nuclei.Frequently, for example, the greatly preponderant proportion of aromaticnuclei obtained in coal acids prepared in the described fashion havebeen found to consist of methylnaphthalene, benzene, biphenyl,naphthalene, phenanthrene, alkyl benzene, benzophenone and toluenenuclei.

The polyfunctional amine compounds that are employed in the practice ofthe invention to prepare the resin-providing coal acids adducts mayadvantageously be selected from the group of polyamines that arerepresented by either of the formulae H N-RNH and H N-(RNHR),,NH whereinR may be any C to C aliphatic or C to C aromatic radical and n is awhole integer. Other functionally equivalent polyamine compounds such aspiperazine and the various substituted piperazines and melamine, inwhich the nitrogen atoms are part of a heterocyclic molecular structure,may also be utilized. In the interests of economy, it is generally anadvantage to utilize relatively low molecular weight aliphaticpolyamines for the preparation of the coal acids adducts. Polyaminesthat may be included in this category include hexamethylene diamine,hexamethylene tetramine, ethylene diamine, diethylene .triamine,triethylene tetramine and the like.

By way of further illustration, a coal acids adduct was prepared bydissolving about 164 grams (2 equivalent weights) of coal acids, havingan average molecular weight of about 250, in about 250 milliliters ofwater and gradually adding to the aqueous coal acids solution, withcontinued eificient mixing, about 116 grams (2 equivalent weights) ofhexamethylene diamine. During the exothermic reaction which ensued, thereaction mass was maintained at a temperature beneath about 120 F. Atthe termination of the reaction, a relatively hard and glassy coal acidsadduct which was completely soluble in water could be obtained bydistilling 01f the water of reaction at temperatures beneath curingtemperatures for the adduct.

A dilute water solution of the hexamethylene diamine/coal acids adductcontaining about percent by weight thereof was applied to a mat of glassfibers that weighed about 3 ounces and had dimensions of about 1 x 4 x 6inches. The excess solution was removed from the mat with the assistanceof a suction box over which the glass fiber mat fit. The resultant mat,containing about 10-15 percent by weight of the resin binder, was curedin an electric oven at a temperature of about 500 F. for an hour. Thecured mat had a light tan colored surface and also had very goodstrength and rigidity. In addition, it had excellent resistance topunking as evidenced by a test in which a red hot copper rivet wasdropped in the test mat in order to observe the speed and degree of burnoff of the binder. Its performance in this respect was superior to thatobtained with a conventional phenolic resin glass fiber binder.

A 70 percent by weight solution of the same adduct in water was mixedwith various batches of AFS 100 Vassar Bank Sand and subsequently driedand screened to prepare coated sand mixtures suitable for shell moldingpurposes that had adduct contents between about 4 and 8 percent byweight. Various types of shell molds were prepared by conventional dumpbox techniques with each of the coated sand mixtures, using patternsheated to temperatures between about 600 and 700 F. with contact timesthereon ranging from to seconds. The pre-formed shell molds weresubsequently thermoset and cured for about 1 minute at a temperature ofabout 700 F. The shell molds that were obtained were strong, goodquality specimens that permitted the preparation of excellent castingswhen they were employed for such purposes.

In a similar manner, sand mixtures containing 4 to 10 percent by weightof the resin were prepared with the percent aqueous coal acids adductsolution and AFS 33 Portage 4060 Sand. The mixtures were wet pressedinto hot top devices which were cured at about 500 F. for l to 4 hours.The resulting structures were found to hold molten iron with ease and tobe readily strippable from the solidified metal upon cooling.

What is claimed is:

1. Thermosetting, cross linkable composition comprised of an adduct ofcoal acids and a polyfunctional amine compound, said polyfunctionalamine compound being selected from the group consisting of those of theformulae H NRNH and wherein R is a radical of the class consisting of 2to 10 carbon atom hydrocarbon aliphatic radicals and 6 to 14 carbon atomaromatic radicals and n is a whole integer, said coal acids being thewater-soluble, mixed aromatic polycarboxylic acids of the class that arethe product of the oxidation of coal, which acids have an averagemolecular weight of about 250, an average equivalent weight of fromabout to about and contain an average of from about 2.5 to 5 carboxylicgroups per aromatic nucleus in their molecule.

2. The composition of claim 1, wherein the adduct consists of aboutequivalent weight proportions of the coal acids and the polyfunctionalamine compound.

3. The composition of claim 1, wherein the polyfunctional amine compoundis hexamethylene diamine.

4. The composition of claim 1, wherein the polyfunctional amine compoundis ethylene diamine.

5. The composition of claim 1, wherein the polyfunctional amine compoundis diethylene triamine.

6. The composition of claim 1, characterized in being thermosetting whenheated to a temperature between about 300 and 600 F.

7. A thermoset, cross-linked resinous product comprising a curedcomposition in accordance with the composition set forth in claim 1.

8. Thermosetting mass for forming integral composite structurescharacterized in being thermosetting when heated to a temperaturebetween about 300 F. and about 600 F. consisting of an inert fillersubstance blended with a resin-producing composition comprised of anadduct of coal acids and a polyfunctional amine compound, saidpolyfunctional amine compound being selected from the group consistingof those of the formulae and H N(R-NHR),,-NH wherein R is a radical ofthe class consisting of 2 to 10 carbon atom hydrocarbon aliphaticradicals and 6 to 14 carbon atom aromatic radicals and n is a wholeinteger, said coal acids being the water-soluble, mixed aromaticpolycarboxylic acids of the class that are the product of the oxidationof coal, which acids have an average molecular weight of about 250, anaverage equivalent weight of from about 75 to about 90 and contain anaverage of from about 2.5 to 5 carboxylic groups per aromatic nucleus intheir molecule.

9. The thermosetting mass of claim 8 containing a minor proportion ofabout 2 percent by weight, based on the weight of the mass, of theresin-producing adduct blended with the inert filler substance.

10. The thermosetting mass of claim 8 containing an amount of theresin-producing adduct blended with the inert filler substance that isadapted to provide between about 2 and 15 percent by weight of resinbinder in the mass when it is cured.

11. The thermosetting mass of claim 8, wherein the inert filler is asilicious filler substance.

12. A thermosetting mass in accordance with that set forth in claim 11,wherein the inert, silicious filler substance is glass fibers.

13. A thermosetting mass in accordance with that set forth in claim 11,wherein the inert, silicious filler substance is sand.

14. Method for the fabrication of thermoset, integral compositestructures which comprises blending an inert filler substance with aminor proportion of about 2 percent by weight, based on the weight ofthe mass, of a resin-providing composition comprised of an adduct ofcoal acids and a polyfunctional amine compound, said polyfunctionalamine compound being selected from the group consisting of those of theformulae H NR-NH and H N(RNHR),,NH wherein R is a radical of the classconsisting of 2 to 10 carbon atom hydrocarbon aliphatic radicals and 6to 14 carbon atom aromatic radicals and n is a whole integer, said coalacids being the water-soluble, mixed aromatic polycarboxylic acids ofthe class that are the product of the oxidation of coal, which acidshave an average molecular weight of about 250, an average equivalentweight of from about 75 to about 90 and contain an average of from about2.5 to 5 carboxylic groups per aromatic nucleus in their molecule; andsequentially subjecting the blend to thermosetting and curing heats atelevated thermosetting and curing temperatures to heat said adduct insaid blend to an actual temperature between about 300 F. and about 600F. until said adduct is cured.

15. The method of claim 14 and including the step of forming the blendedingredients to a desired shape prior to subjecting them to saidthermosetting temperature.

16. The method of claim 14, wherein the inert filler substance and theresin providing adduct are dry-blended.

17. The method of claim 14, wherein the inert filler substance isblended with the resin-providing adduct by mixing a solution of thelatter with the former.

18. Method for the preparation of composite glass fiber structures whichcomprises applying to a mass of glass fibers a solution of aresin-providing composition comprised of an adduct of coal acids and apolyfunctional amine compound, said polyfunctional amine compound beingselected from the group consisting of those of the formulae H NR-NH andwherein R is a radical of the class consisting of 2 to 10 carbon atomshydrocarbon aliphatic radicals and 6 to 14 carbon atom aromatic radicalsand n is a whole integer, said coal acids being the water-soluble, mixedaromatic polycarboxylic acids of the class that are the product of theoxidation of coal, which acids have an average molecular weight of about250, an average equivalent weight of from about 75 to about 90 andcontain an average of from about 2.5 to carboxylic groups per aromaticnucleus in their molecule; draining excess solution from the mass ofglass fibers so that between about and 15 percent by weight, based onthe final weight of the composite structure, of the cured resin from theresin-providing adduct is intimately blended throughout the mass ofglass fibers; and subsequently subjecting the blended mass tothermosetting and curing heats at elevated thermosetting and curingtemperatures to heat said adduct applied to said glass fibers in saidmass to an actual temperature between about 300 F. and about 600 F.until said adduct is cured.

19. Method for the fabrication of refractory structures which comprisesblending sand with a solution of a resinproviding composition comprisedof an adduct of coal acids and a polyfunctional amine compound in anamount to provide between about 3 and 8 percent by weight, based on theweight of the refractory structure, of the cured resin from theresin-providing adduct in the sand blend, said polyfunctional aminecompound being selected from the group consisting of those of theformulae H2N-RNH2 and 7LNH2 Wherein R is a radical of the classconsisting of 2 to 10 carbon atom hydrocarbon aliphatic radicals and 6to 14 carbon atom aromatic radicals and n is a whole integer, said coalacids being the water-soluble, mixed aromatic polycarboxylic acids ofthe class that are the product of the oxidation of coal, which acidshave an average molecular weight of about 250, an average equivalentweight of from about 75 to about and contain an average of from about2.5 to 5 carboxylic groups per aromatic nucleus in their molecule;forming the blended sand to a desired shape; and subsequently subjectingthe formed mass to thermosetting and curing heats at elevatedthermosetting and curing temperatures to heat said adduct blended withthe sand to an actual temperaure between about 300 F. and about 600 F.until said adduct is cured.

20. The method of claim 19 wherein the refractory structure is a shellmold and including the steps of drying the wet blended sand to agranular, free-flowing mass after mixing it intimately with the solutionof the resinproviding adduct and pre-forming the shell mold on a patternheated to a temperature between about 500 F. and about 800 F. for aperiod of time between about 20 and about 60 seconds prior tothermosetting and curing the resulting shell mold structure.

Valyi: After Three Years: Developments in Shell Molding, AmericanFoundryman, May 1954, pages 138-143.

1. THERMOSETTING, CROSS LINKABLE COMPOSITION COMPRISED OF AN ADDUCT OFCOAL ACIDS AND A POLYFUNCTIONAL AMINE COMPOUND, SAID POLYFUNCTIONALAMINE COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF THOSE OF THEFORMULAE H2N-R-NH2 AND